Apparatus for the removal of salt from sea water



April 20, 1965 J. E. sAuNDERs APPARATUS FOR THE REMOVAL 0F SALT FROM SEA WATER Filed Aug. 5, 1965 JAMES E. 54m/D525 al BY%(/. AGEN-r part of the present specication.

United States Patent O 3,178,900 APPARATUS FOR THE REMOVAL F SALT FROM SEA WATER James E. Saunders, 1739 Armour Laue, Redondo Beach, Calif. Filed Aug. 5, 1963, Ser. No. 299,718 Claims. (Cl. 62-123) The invention herein described pertains primarily to the separation of fresh water from sea water and particularly to the apparatus and means by which this is accomplished.

Processes heretofore suggested or tried for the separation of fresh water from sea water have usually been very complicated or expensive and have not been of such a nature that the processes could be employed both 0n a large or a small scale. The apparatus and method of the present invention avoid these drawbacks.

One object of the instant invention is to provide simple apparatus for the removal of salt and other minerals from sea water.

Another object is to provide apparatus of the type described that is so simple that it may be used by campers or on small privately owned boats, or in multiple unit installations for effecting fresh water separation on a large scale.

An additional object is to provide a method for the afore-mentioned purposes that may be applied in a wide variety of forms and applications.

A further object is the provision of a system for salt removal that is not only simple in operation but very inexpensive in its initial cost.

Still another object is to achieve the aforementioned objectives by means of a difference in air pressure on opposite sides of a wall of ice, such difference being obtained either by increasing the air pressure on one of said sides above that of the surrounding atmosphere by means of compressed air, or by decreasing the pressure on one of said sides below that of the atmosphere by means of a partial vacuum in a chamber separated from air of atmospheric pressure by a wall of ice formed by freezing the sea water from which the salt is to be removed.

This invention possesses many other advantages and has other objects which may be made more clearly apparent from a consideration of illustrative embodiments of the invention. For this purpose, such embodiments are shown in the drawings accompanying and forming a These embodiments will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is best deiined by the appended claims.

In the drawings:

FIGURE l is a longitudinal sectional view of the principal novel components of one embodiment of the invention, with other components shown in diagrammatic or block form;

FIG. 2 is a section taken on line 2-2 of FIG. l; and

FIG. 3 is a horizontal cross-section through the freezing compartment and evaporator of a different embodiment of the invention. I

In the simple embodiment illustrated in FIG. 1, the cylinder 11 surrounds two other smaller cylinders 12 and 13 secured therein in longitudinal alignment with each other.

The lower cylinder 12 has a closed bottom and an open top, while the aligned upper cylinder 13 has a closed top and an open bottom. Cylinder 12extends below the bottom of the outer cylinder 11 in order to facilitate the connection thereto of pipe 14, this arrangement 3,178,900 Patented Apr. 20, 1965 ICC making it unnecessary for the pipe 14 to pass through the outer cylinder 11 in order to communicate with the inner cylinder 12. The purpose of the pipe 14 Will be disclosed hereinafter.

The cylinder 13 extends above the top end of the outer cylinder 11 to simplify the connection thereto of pipe 15, which, like pipe 14, will be discussed hereinafter when its relationship to other elements of the equipment may be more readily apparent.

The bottom of cylinder 11 is sealed around the cylinder 12 in any convenient manner, the specific arrangement' shown in the figure employing an annular disc or ring 16 sealed to the walls of the cylinder 11 at its outer edges, the inner edge 17 of ring 16 being appropriately sealed to the periphery of cylinder 12 near its lower end. The cylinder 12 has a flange or ring 18 extending laterally from its open top end, the outer edges of this liange being sealed to the inner walls of the outer cylinder 11.

It will be observed that the structure just described provides a confined annular area or region 19 surrounding the cylinder 12.

The upper end of cylinder 13 is sealed by a cover member 20, and the upper end of the outer cylinder 11 is sealed by means of a centrally apertured disc ,21 whose periphery is secured to the walls and upper end of the outer tube or cylinder 11 and whose inner edge is sealed to the periphery of the inner cylinder 13. An outwardly extending flange 22 is attached to the open lower end of cylinder 13, and the periphery of this flange is sealed to the inner walls of the outer cylinder 11. It will be apparent that the structure just described in connection with cylinder 13 is the symmetrical counterpart of the similar structure last previously described in connection with the lower inner cylinder 12; and it will be clear that an annular space 30 is thereby provided around the cylinder 13 just as the similar annular area 19 was provided around the lower inner cylinder.

An air inlet tube 23 passes through the top 20 of cylinder 13 and extends downward to a point below the lower end of cylinder 13. The bottom of pipe 23 is thus disposed between the facing ends of cylinders 11 and 12. A resilient sealing sleeve 24, the purpose of which will later be explained, is secured to the periphery of tube 23 at the lower end of the tube.

An elongated member 25, preferably a round rod, is secured to the bottom of cylinder 12 and extends upward to a position approximately even with the top end of this cylinder. The purpose of this coaxially disposed rod together with that of certain other components will probably be more easily understood if the operation of the Jportons of the apparatus already described is first set ort The sea water from which the salt is to be extracted is rst frozen in the column 12, and appropriate means are provided to cool the sea water before it is introduced into the tube 12. These means include conduits 26 and 28, between which is interposed a pump 27 that pumps the incoming sea water through these conduits into the heat exchanger 29 where the water is cooled by means hereinafter set forth. From the heat exchanger the cooled sea water passes through conduit 14 into the lower portion of cylinder 12. Here the cool sea water is frozen by a refrigeration system now to be described.

In this refrigeration system, the region 30 functions as a condenser and the region 19 as an evaporator. The top portions of regions 19 and 30 are connected by tubes 31 and 32 and the compressor 33 which is interposed between them. Another tube or conduit 35 connects the bottom portions of the annular regions 30 and 19. These annular regions, the tubes 35, 31 and 32 and the compressor 33 contain the refrigerant. This refrigerant, which is in liquid form in the annular region 19, passes through conduit 31 to the compressor 33. The action of the compressor greatly heats the refrigerant, which proceeds as a hot gas through tube 32 in the direction of the arrow 33 into the region 30 where the gas condenses into a liquid again. The liquid refrigerant leaves the condenser through conduit 35 from which it flows into the lower part of the annular evaporating region 19 where the evaporation of the refrigerant lowers its temperature sufficiently to freeze the already cooled sea water 39 in the cylinder 12.

The frozen sea water rises as a column of ice in the cylinder 12 under the pressure of the cooled sea water that is pumped into the bottom of the cylinder. This column, of course, has a coaxial recess therein formed by the rod 25. As the column of ice continues to rise, it encircles the sealing sleeve 24 on the lower end of the air inlet tube 23 and thence passes through the open bottom end of the upper cylinder 13.

The frozen sea water, in the region between the cylinders 12 and 13 is of course a rigid tube of ice. A resilient sealing annulus 40 embraces this column in the region that immediately surrounds the sealing sleeve 24. The complete function of the sealing annulus 17 will later become apparent. Suffice it to say now, however, that it forms the upper border of an annular compartment 43. The flange 18 forms the bottom of this compartment.

As hereinbefore stated, the salts in the frozen solid may be removed either by suction or air pressure or both. When either method is employed, the pressure of the air in the space 42 between the lower end of the tube 23 and the top end of member 25 is greater than the air pressure in the annular space 43 around the column of ice 44. This difference in air pressure is provided either by pump 45, pump 46, or both.

If air pressure is to be employed, pump 45 pumps air through the air inlet tube 23 into the space 42. If the air pressure in the annular region 43 is at or below the air pressure in the surrounding atmosphere, the compressed air from the space 42 on the inside of the tubular Ycolumn of ice moves laterally through this column carrying the salt and some of the sea water from the column with it into the annular space 43. This brine then proceeds from the bottom of the space 43 through the tube 45 into the heat exchanger 29 either with or without the help of the pump 46. This cold brine ows over the coils 47 through which the incoming sea water passes, thus materially cooling the entering sea water before it enters the freezing space 39 surrounding member 25.

The waste water from the heat exchanger 29 passes through tube 41 into the drain 49. In a commercial plant, the waste water may be processed for the recovery of the minerals.

If suction alone is to remove the salt from the frozen column of sea water, pump 46 may provide the suction, and the air in the space 42 may remain at atmospheric pressure. In this case, the pump 45 need not be employed, the tubular inlet 23 then merely serving as a means whereby the confined space 42 may communicate with the outside atmosphere.

The hot refrigerant gasses in the upper portion of the condensing area 30 move downward through this area toward the conduit 35, meanwhile passing the rising column of ice within the cylinder 13. The heat exchange that here takes place gradually melts the column of ice 44 as itrises in the cylinder 13 past the warm gasses in the surrounding condenser 30.

The portion of the column of ice above the sealing annulus 40 isof course relatively free from salt, and it is accordingly such water that flows out of the upper portion of the cylinder 13 through the conduit 15 to such storage as may be provided.

In addition to performing the function of providing the upper boundary for the separation compartment 43,

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the sealing annulus 40 serves to catch any fresh water that may flow down the outside of the ice column 44 between this column and the inner walls of the cylinder 13. Such water as may seep into the region 59 may be drained olf in any appropriate manner.

It is of course not essential to the use of my process that the frozen column from which the salts are to be separated be tubular in form, or even round. It is essential, however, that there be a freezing compartment from which a column of ice arises and that there be a difference in the air pressure onopposite sides of the wall of ice. Accordingly, the space 42 and the compartment 43 may merely be air compartments separated by the rising column of ice. In this case, member 25 may be considered to constitute one wall of a container in which the ice is frozen, with what has been illustrated as one wall of the cylinder 12, say the wall 4S, forming the opposite wall of such compartment. This arrangement is illustrated in FIG. 3 where the counterpart of member 25 in FIG. l is the wall 25 and where the evaporator has been given the designation 19 with the column of frozen water 39-44 rising between them,

The amount of salt that must be removed from the sea water depends of course upon the use that is to be made of it, various industrial purposes or cooking, for example, requiring a lesser degree of purity than drinking water. The degree of salinity of the water that has passed through the equipment is shown by the indicator 5S, FIG. l. This is connected in series with a pair of spaced contacts 52 and 53 carried by the insulating member 51 mounted on the inner wall of cylinder 13. Conductor 55 connects the indicator to contact 52, and conductor 54 connects contact 53 to the current source 54 which in turn is connected to the indicator by conductor 57. The current passing through this series circuit depends, of course, upon the sali-nity of the water.

If one traversal of the equipment has not removed sufficient salt, the water may of course be passed through the cylinders one or more additional times until the desired degree of purity has been obtained. This may be effected automatically by connecting pipe 15 to a 3-way electrically operated valve having one of its two outlets connected to a storage reservoir and its other outlet connected to pipe 14, the 3-way electrically operated valve being energized through a current-sensitive relay connected to conductors 55 and 57 and the relay being set to keep the valve so turned that it will direct the water from pipe 15 into pipe 14 whenever the salinity of the water is above a pre-selected value.

Components of still other shapes, forms and types may be used for practicing my invention, as will be apparent to those skilled in the art; and various substitutions, transpositions and additions may of course be made without departing from the broad spirit of my invention as succinctly set forth in the appended claims.

The inventor claims:

l. In apparatus for separating fresh water from sea water: a rst elongated vertical cylinder; a second elongated vertical cylinder materially shorter than said first cylinder, said second cylinder affixed within said first cylinder with its longitudinal axis parallel to the longitudinal axis of said rst cylinder, the lower end of said second cylinder being closed; a rst means closing the bottom of said rst cylinder, said first means comprising a first ring encircling said second cylinder and sealed thereto; a second ring interposed between, and sealed to, said rst and second cylinders adjacent the top of said second cylinder; an elongated member so supported within said second cylinder that said member and second cylinder define an annular space between the member and the second cylinder; a third cylinder longitudinally aligned with said second cylinder but spaced therefrom; a cap closing the top of said third cylinder; a second means closing the top of said rst cylinder, said second means comprising a third ring encircling said third cylinder and sealed thereto; a fourth ring interposed between, and sealed to, said first and third cylinders adjacent the bottom of said third cylinders; an air conduit passing through said cap and traversing said third cylinder in longitudinal alignment with said member but spaced therefrom; a first sealing annulus encircling the lower end of said conduit, the peripheral contour and circumference of said first annulus being substantially identical to those of said member; a second sealing annulus encircling said first annulus, but spaced therefrom, the periphery of said second annulus being secured to the inner walls of said first cylinder; a pump for pumping sea water into the lower end of said second cylinder; a heat exchanger operatively interposed between said pump and said second cylinder for reducing the temperature of the water entering said second cylinder from said pump; a refrigerant compressor operatively interposed between the top of the annular region surrounding said second cylinder and the top of the annular recess surrounding said third cylinder; said annular region comprising a liquid refrigerant evaporator; a refrigerant in said recess and said region; said recess acting as a condenser for the refrigerant received through said compressor from said region; an air pump for pumping air into said conduit; a pipe for carrying the condensed refrigerant from the bottom of said recess to the bottom of said region for freezing the sea water in said second cylinder, the frozen sea water rising in the form of a tubular column around said member as a result of the force of the pressurized sea water entering the bottom of the second cylinder; the compressed air received in said tubular column from said conduit in the space between said member and the lower end of said conduit acting to force salt in solution from the portions of the column surrounding said space into the annular area around said column between said second cylinder and said second annulus; a first pipe for carrying the cold salt Water from said area t0 said heat exchanger for cooling the incoming sea water; and a second pipe communicating with the interior of said third cylinder for removing the fresh water obtained from the de-salted ice column rising in said third cylinder and melting therein as a result of the heat received from the gaseous refrigerant entering the adjoining upper portion of said recess from said compressor.

2. In apparatus for separating fresh water from sea water: an elongated first tank having a closed bottom and an open top and comprising a pair of parallel spaced vertical members; a second tank also comprising a pair of parallel spaced vertical members, but having a closed top and an open bottom, the spaced members of said second tank being vertically aligned with the spaced members of said first tank but longitudinally spaced therefrom;

means for introducing sea water under pressure into the lower portion of said first tank; means for freezing the sea water as it rises in said first tank; means for directing compressed air into a first enclosed area defined in part by a portion of the column of frozen water proceeding from said first tank into said second tank through the region between the two tanks; means for withdrawing salt Water from a second enclosed area defined in part by the surface of said column that is opposite from said portion, said salt water being forced from said column by the compressed air on one side thereof; means for melting the column of de-salted ice as it rises in said second tank; and means for withdrawing from said second tank the fresh water produced by the melting column of ice.

3. In apparatus for separating fresh water from sea water: an elongated first tank having a closed bottom and an open top and comprising a pair of parallel spaced vertical members; a second tank also comprising a pair of parallel spaced vertical members, but having a closed top and an open bottom, the spaced members of said second tank being vertically aligned with the spaced members of said first tank but longitudinally spaced therefrom; means for introducing sea water under pressure into the lower portion of said first tank; means for freezing the sea water as it rises in said first tank, thus forming a column of ice that moves from said first tank into said second tank throughV the region between the two tanks, said column acting as a boundary between two enclosed areas on opposite sides of the column, said areas being transversly spaced with respect to the direction of movement of the column; means for creating and maintaining an air-pressure dierential between said areas to force salt water from said column into the area having the lowest air pressure; means for melting the column of desalted ice as it rises in said second tank in response to the pressure of the incoming sea water below the column; and means for withdrawing from said second tank the fresh water produced by the melting column of ice.

4. In apparatus for separating fresh water from sea water: an elongated first tank having a closed bottom and an open top and comprising a pair of parallel spaced vertical members; a second tank also comprising a pair of parallel spaced vertical members, but having a closed top and an open bottom, the spaced members of said second tank being vertically aligned with the spaced members of said first tank but longitudinally spaced therefrom; means for introduing sea water under pressure into the lower portion of said first tank; means for freezing the sea water as it rises in said first tank, thus forming a column of ice that moves from said first tank into said second tank through the region between the two tanks, said column acting as a boundary between two enclosed areas on opposite sides of the column, said areas being transversely spaced with respect to the direction of movement of the column; means for creating a partial vacuum in one of said areas to draw salt water from said column into said one of said areas; means for melting the column of de-salted ice as it rises in said second tank; and means for withdrawing from said second tank the fresh water produced by the melting column of ice.

S. In apparatus for separating fresh water from sea water: a first elongated vertical cylinder; a second elongated vertical cylinder materially shorter than said first cylinder, said second cylinder affixed within said first cylinder with its longitudinal axis parallel to the longitudinal axis of said first cylinder; the lower end of said second cylinder being closed; a first means closing the bottom of said first cylinder, said first means comprising a first ring encircling said second cylinder and sealed thereto; a second ring interposed between, and sealed to, said first and second cylinders adjacent the top of said second cylinder; an elongated member so supported within said second cylinder that said member and second cylinder defiine an annular space between the member and the second cylinder; a third cylinder longitudinally aligned with said second cylinder but spaced therefrom; a cap closing the top of said third cylinder; a second means closing the top of said first cylinder, said second means comprising a third ring encircling said third cylinder and sealed thereto; a fourth ring interposed between, and sealed to, said first and third cylinders adjacent the bottom of said third cylinder; an air inlet conduit passing through said cap and traversing said third cylinder in longitudinal alignment with said member but spaced therefrom; a first sealing annulus encircling the lower end of said conduit, the peripheral contour and circumference of said first annulus being substantially identical to those of said member; a second sealing annulus encircling said first annulus, but spaced therefrom, the periphery of said second annulus being secured to the inner walls of said first cylinder; a pump for pumping sea water into the lower end of said second cylinder; a heat exchanger operatively interposed between said pump and said second cylinder for reducing the temperature of the water entering said second cylinder from said pump; a refrigerant compressor operatively interposed between the top of the annular region surrounding said second cylinder and the top of the annular recess surrounding said third cylinder;

said annular region comprising a liquid refrigerant evaporator; a refrigerant in said recess and said region; said recess acting as a condenser for the refrigerant received through said compressor from said region; a pipe for carrying they condensed refrigerant from the bottom of said recess to the bottom of said region for freezing the sea Water in said second cylinder, the frozen sea Water rising in the form of a tubular column around said member as a result of the force of the pressurized sea Water `entering the bottom of the second cylinder; the inner edge of said second annulus slidably engaging said column of area to said heat exchanger for cooling the incoming sea Water; and a second pipe communicating with the interior of said third cylinder for-removing the fresh water obtained from the de-salted ice column rising in Said third cylinder and melting therein as a result of the heat received from the gaseous refrigerant entering the adjoining upper portion of said recess from said compressor.

References Cited by the Examiner UNITED STATES PATENTS Re. 23,810 3/54 Schmidt 62-124 X 2,240,463 4/41 Schlumbohm 62-58 2,854,494 9/58 Thomas 62-124 X ROBERT A. OTJEARY, Primary Examiner. 

2. IN APPARATUS FOR SEPARATING FRESH WATER FROM SEA WATER; AN ELONGATED FRIST TANK HAVING A CLOSED BOTTOM AND AN OPEN TOP AND COMPRISING A PAIR OF PARALLEL SPACED VERTICAL MEMBERS; A SECOND TANK ALSO COMPRISING A PAIR OF PARALLEL SPACED VERTICAL MEMBERS, BUT HAVING A CLOSED TOP AND AN OPEN BOTTOM, THE SPACED MEMBERS OF SAID SECOND TANK BEING VERTICALLY ALIGNED WITH THE SPACED MEMBERS OF SAID FIRST TANK BUT LONGITUDINALLY SPACED THEREFROM; MEANS FOR INTRODUCING SEA WATER UNDER PRESSURE INTO THE LOWER PORTION OF SAID FIRST TANK; MEANS FOR FREEZING THE SEA WATER AS IT RISES IN SAID FIRST TANK; MEANS FOR DIRECTING COMPRESSED AIR INTO A FIRST ENCLOSED AREA DEFINED IN PART BY A PORTION OF THE COLUMN OF FROZEN WATER PROCEEDING FORM SAID FIRST TANK INTO SAID SECOND TANK THROUGH THE REGION BETWEEN THE TWO TANKS; MEANS FOR WITHDRAWING SALT WATER FROM A SECOND ENCLOSED AREA DEFINED IN PART BY THE SURFACE FO SAID COLUMN THAT IS OPPOSITE FROM SAID PORTION, SAID SALT WATER BEING FORCED FROM SAID COLUMN BY THE COMPRESSED AIR ON ONE SIDE THEREOF; MEANS FOR MELTING THE COLUMN OF DE-SALTED ICE AS IT RISES IN SAID SECOND TANK; AND MEANS FOR WITHDRAWING FROM SAID SECOND TANK THE FRESH WATER PRODUCED BY THE MELTING COLUMN OF ICE. 